Water vapor is also an important gas to consider when studying the atmosphere. The amount of water vapor found in the air remains constant on average, however, it can vary greatly from one place to another. Some parts of the Earth are prone to high humidity levels, while other locations have very dry air. What affect does this water vapor have on the atmosphere? Much of what we consider weather is caused by water vapor. The clouds in the sky are largely made up of it, and it is the condensation of this vapor into droplets that creates rain and snow. Water vapor also has a significant impact on temperature.

Consider your body. When your body becomes too hot, it has a natural built in mechanism for cooling itself down. This mechanism is known as sweating. As the sweat evaporates off of your body, it carries the excess heat with it into the air. The same happens with the surface of the Earth. As water evaporates, heat is carried from the Earth’s surface into the atmosphere. Likewise, as rain falls down, heat can be transferred from the atmosphere back to the ground.